1. Field of the Invention
The present invention relates to an automatic composition apparatus, an automatic composition method and a storage medium.
2. Description of the Related Art
There is known a technology for automatically compose music based on a motif melody consisting of a plurality of note data items. In the related art, for example, the following technology is known (for example, a technology disclosed in JP-A-2002-032080). If a certain chord progression is selected from a database retaining chord progressions of a specific key, and a motif is input in a certain key, a motif key is detected from the input motif. Based on the detected motif key, data on the chord progression is transposed into the motif key. Then, in a melody generating block, based on the input motif and the chord progression after the transposition into the motif key, a melody is generated in the motif key. Also, the motif is transposed into the specific key based on the detected motif key, and a melody of the specific key is generated based on the chord progression of the specific key and the transposed motif, and then is transposed into a melody of the motif key.
Also, in the related art, the following technology is known (for example, a technology disclosed in JP-A-H10-105169). Notes having lengths equal to or greater than that of a quarter note are extracted from musical performance data for karaoke and guide melody data which are music data, and the distributions of frequencies of the pitch names (C to B) of the extracted notes are aggregated. The frequency distributions are compared to a major judgment scale and a minor judgment scale. Then, the data is judged to have a key in which the tonic note (scale note) exists at a place where the highest coincidence in distribution shape is attained. Subsequently, based on the result of the key judgment and the guide melody data, harmony data is generated. Then, based on the harmony data, a harmony voice signal is produced.
However, in the above described technologies according to the related art, it is implicitly assumed that a motif melody can be specified in a certain key. For this reason, it is impossible to handle modulation in a motif, mode-like melodies, atonal motifs, and the like. Also, since the key judgment is a method based on the distribution of pitches, sometimes, an accurate correspondence relation may not be obtained. For example, “re, do, si, la, and sol” and “sol, re, la, si, and do” have the same pitch distribution, but should be considered as G major and C major, respectively.